Cottrell’s Windows & Doors

  • Replacement UPVc windows

    A++ rated double & tripple glazing

    Double glazing and Triple glazing

  • Box sash replacement

    Bespoke UPvc sliding sash replacements

    Sliding Box sash replacements

  • Aluminium Bi-fold Doors

    High quality bespoke Bifold doors in a full range of colours

    Custom Additions icon

  • Composite Doors

    Insulated ,security composite doors with a full range of options

    Composite door

Our Projects

  • tripple aluminium patio

    Three-pane sliding Ali door

  • Rio Flush casements

    Rio Flush casement windows

  • Utility door

    Utility door with side window

  • Box sash bay

    Structual 3 part bay window

  • Cottage-style geo

    Cottage-style Geo window

  • cottage

    Traditional windows and new composite door

A brick house exterior with white-framed windows, a black gutter, a ladder, flower pots, and a garden with purple flowers.

We are pleased to help with your next project, whether it's a single window or a full house of replacements.

With over 35 years in the industry and hundreds of happy customers across Alton and the surrounding Hampshire / Surrey area, we believe in quality products fitted with quality workmanship — all backed by a 10-year insurance-backed warranty and CERTASS registration.

We install A-rated double and triple glazing in uPVC or aluminium, insulated Hallmark composite doors with a full range of colours and finishes, French doors, bi-fold doors, and sliding patio doors. We also replace failed misted sealed units in existing frames.

Most single window or door replacements are completed within a day; larger projects are scoped and scheduled during your free, no-obligation quote visit.

Get in touch for honest advice and a free quote — no pressure, no obligation.

Ready to upgrade your windows?

Our family-run business will be pleased to help you with your latest project be it a small or large installation.

Please contact us for all your double glazing needs and we will be happy to help with advice and free no obligation quotes.

Still have questions? Take a look at the FAQ or reach out anytime.

If you’re feeling ready, please fill out our FREE quote form.

Get your FREE quote now!

  • “A” plus energy rated double glazing, tripple glazing, Aluminium or UPVc windows and doors. Insulated Halmark composite doors with security locking along with a wide range of colours and finish options, French doors , Bi-fold doors and sliding patio doors.

  • Yes, we also replace broken down misted sealed units into existing frames.

  • With over 35 years in the industry and 100’s of very happy customers + reviews, we believe in quality products with quality workmanship and all backed up by a 10 year insurance backed warranty along with CERTASS registration.

  • You can reach us anytime via our contact page, phone or email. We aim to respond quickly—usually within one business day.

  • We offer flexible pricing based on project type and complexity. After an initial conversation, we’ll provide a transparent quote with no hidden costs.

All our work is carried out by ourselves. We take pride in providing a professional service with customer satisfaction our top priority. We can cover every aspect and undertake any project with confidence.

With a full range of windows and doors in all colours and finishes, we should have something ideal for your project.

Replacing windows and doors for over 35 years

with 10 year insurance backed warranty & CERTASS registration

A red front door with a silver ring door knocker, white door frame, and a silver mail slot, set in a textured white wall. To the left of the door is a small section of black asphalt and a manhole cover, with some small green plants and dirt at the base of the wall.
A sliding glass door leading to an outdoor patio with wooden flooring and a brick wall. Inside the room, beige sofa with a blanket, wooden ceiling, yellow wooden fence, and neighboring houses are visible through the glass.

Our Catalog

  • "Phil did an outstanding job on our porch, honestly couldn't recommend him more highly. He was friendly, professional and listened to what we wanted. The end result looks fantastic and the whole experience was smooth and hassle-free. If you need porch work done or new windows and doors, call Phil. You won't regret it!"

    — Elizabeth B, 29th June 2026 — 10/10

    New porch fitted with brickwork, windows and front door

  • "Cottrell’s Windows. Did a fantastic job, they were very professional. We are very happy with the outcome, the windows look great. I will be using them again."

    — Verified reviewer, 13 January 2025 — 10/10

    New Windows through-out the house.

  • "Cottrell’s completed a survey on a recent window installation by another company where we had a negative experience. Phil gave confident advice on whether the work met building control / regulations and reasonable standards. We then chose Cottrell’s to remove the previous windows and complete a new installation. We are over the moon with the new and end result and can see a real difference in standards. Phil went above and beyond and ensured the making good was completed thoroughly, including some tricky tile work. House left tidy, a friendly and professional service provided throughout."

    — Verified reviewer, 24 September 2023 — 10/10

    Independent survey, replacement and new installation of windows

  • "Phil was friendly and relaxed from the start of the process wich was very reasuring. The finished product is testimony to his professional way of working. I would highly recommend Cottrell's Windows and the next itme i need new windows and doors I will be contacting Phil again"

    — Charlotte T, June 2024 — 10/10